This invention pertains to orienting apparatus normally used down hole during directional drilling activities. Adjustments include relative rotation of opposite ends of the sub or, in an alternate configuration, includes changes in the bend angle of the sub.
When drilling directional wells or maintaining direction and angle of progressing drilling of earth bore holes it is often necessary to introduce bends in the drill string. The bends are usually near the drill head. Sometimes, the bends are within drilling motor bodies. Apparatus of the patents cited above are examples of contrivances installed in drill string components to accomplish the needed bend, or rotational relationship of opposite ends of the related drill string.
The tools related to the cited patents have some features that invite errors when making changes in the field to adjust the deflection or orientation angles. The tools are calibrated at the factory and scribed to indicate the amount of deflection angle to be achieved when adjusted later in the field. Problems arise when the indicator ring itself is removed from a spline retained relationship with a major component that is essential to adjustment but is not visible from outside the assembled tool. The details of construction presented later herein will clarify that relationship and the means to prevent loss of calibration in the field, during adjustments.
There are three major functional components, an arbor, or generally central tubular member, with male threads on each end and a generally tubular mating box terminal on each end. The threads on one end of the arbor, and their mating box threads, differ in pitch from the threads on the opposite end.
The threaded boxes are run onto the related mating pin end until both box faces abut a spacer ring between the two. The spacer ring, defined herein as an indicator ring, is free to slide axially but it is rotationally connected to the arbor by splines. If the box with the finer thread is backed away from the indicator ring by a specific rotational amount, the coarser thread of the opposite box requires less rotational adjustment to again abut the spacer ring. Consequently, the opposite ends of the tool will then have a changed rotational relationship. Change in the rotational relationship, in one configuration, changes the bend angle within the sub. Change in the rotational relationship, in the other configuration, changes the rotational relationship of opposite ends of the sub.
If the tool is used only for changing the rotational relationships of the opposite ends of the tool, the adjustment just described changes the drill head related tool face relative to the drill string above the tool.
If the tool is used to adjust the bend angle of the drill string, within the tool, the box threaded terminal ends will have a deflection angle built in. The female threads of the box is symmetrical about one centerline and the continuing end of that terminal has a centerline that crosses the thread related centerline at a selected angle, often at about two degrees. When the tool is shop calibrated, the zero deflection relationship is established such that all center lines lie in the same plane, but the extending ends depart the thread center line in opposite directions. There is a minor jog in the general centerline but the continuing center lines are parallel. There is, then, no deflection angle in the overall assembly. The small jog is without effect.
To adjust the tool to a specified angle, one end is loosened from the abutting situation, and the opposite end is run onto the arbor until the abutting relationship is re-established. The tool then has a deflection angle that depends upon the amount of rotation given to the first end loosened. That amount of deflection is then scribed upon the ring separating the abutting faces of the box threaded terminal ends. The actual manipulation differs somewhat from this simplified description to clarify basic functions. Details that enable the use of the locking pin P will follow herein.
The tool, as presently improved, simplifies the adjustment by providing an indexing pin protruding from the abutting face of a first terminal end. The calibrating ring then has a series of holes that can accept the pin. The series of holes are peripherally spaced such that each hole will correspond with an amount of rotation of the arbor within the first terminal end that will yield a selected deflection when the assembled tool is torqued together for use. The manipulation is the same for the version of the tool that adjusts only the rotational relationship of opposite ends of the sub.
The ring can be moved axially on the arbor, along the connecting splines to allow the ring to rotate clear of the protruding pin after the second box is backed away from the indicator ring. The indicator ring is then rotated, to rotate the spline connected arbor within the first end box threads. With the chosen rotation accomplished, the ring slides along the spline to abut the face of the first end, with the pin sliding into the prepared hole in the ring abutting face. The second box end is then run into abutment, tightened and locked in place with screws that extend radially through the box wall to engage the arbor. The adjustment is complete.
The pin accepting holes in the ring correspond with a scribe line visible on the outer surface of the ring. The deflection angle achieved by the adjustment has a corresponding number stamped at the scribe line. The orienting version of the sub has similar markings on the ring relative to rotational changes of opposite ends of the sub.
Retaining rings on the arbor are situated such that the ring can move an amount needed for field adjustment but the ring will not lose the splined relationship with the arbor established during shop calibration. When used in the field, the abutting faces wear or distort, in time. The retaining ring can be removed in the shop and the indicator ring can be moved axially to clear the splines and can be rotationally repositioned on the arbor to restore calibration accuracy. The loss of calibration is a slow process and is detected when being dresses in the shop for return to the field.
The documentation supplied with the tool indicates the angular situation of the tool in light of the numbers stamped on the indicator ring that coincides with a scribe line on the box of the first end.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached claims and appended claims.